////
This guide is maintained in the main Quarkus repository
and pull requests should be submitted there:
https://github.com/quarkusio/quarkus/tree/master/docs/src/main/asciidoc
////
= Quarkus - Application Initialization and Termination

include::./attributes.adoc[]

You often need to execute custom actions when the application starts and clean up everything when the application stops.
This guide explains how to:

* be notified when the application starts
* be notified when the application stops

== Prerequisites

To complete this guide, you need:

* less than 10 minutes
* an IDE
* JDK 1.8+ installed with `JAVA_HOME` configured appropriately
* Apache Maven 3.5.3+



== Solution

We recommend that you follow the instructions in the next sections and create the application step by step.
However, you can go right to the completed example.

Clone the Git repository: `git clone {quickstarts-clone-url}`, or download an {quickstarts-archive-url}[archive].

The solution is located in the `lifecycle-quickstart` {quickstarts-tree-url}/lifecycle-quickstart[directory].

== Creating the Maven project

First, we need a new project. Create a new project with the following command:

[source,shell,subs=attributes+]
----
mvn io.quarkus:quarkus-maven-plugin:{quarkus-version}:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=lifecycle-quickstart \
    -DclassName="org.acme.events.GreetingResource" \
    -Dpath="/hello"
cd lifecycle-quickstart
----

It generates:

* the Maven structure
* a landing page accessible on `http://localhost:8080`
* example `Dockerfile` files for both `native` and `jvm` modes
* the application configuration file
* an `org.acme.events.GreetingResource` resource
* an associated test

== Listening for startup and shutdown events

Create a new class named `AppLifecycleBean` (or pick another name) in the `org.acme.events` package, and copy the
following content:

[source,java]
----
package org.acme.events;

import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.event.Observes;

import io.quarkus.runtime.ShutdownEvent;
import io.quarkus.runtime.StartupEvent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@ApplicationScoped
public class AppLifecycleBean {

    private static final Logger LOGGER = LoggerFactory.getLogger("ListenerBean");

    void onStart(@Observes StartupEvent ev) {               // <1>
        LOGGER.info("The application is starting...");
    }

    void onStop(@Observes ShutdownEvent ev) {               // <2>
        LOGGER.info("The application is stopping...");
    }

}
----
1. Method called when the application is starting
2. Method called when the application is terminating

TIP: The events are also called in _dev mode_ between each redeployment.

NOTE: The methods can access injected beans. Check the {quickstarts-blob-url}/lifecycle-quickstart/src/main/java/org/acme/events/AppLifecycleBean.java[AppLifecycleBean.java] class for details.

=== What is the difference from `@Initialized(ApplicationScoped.class)` and `@Destroyed(ApplicationScoped.class)`

In the JVM mode, there is no real difference, except that `StartupEvent` is always fired *after* `@Initialized(ApplicationScoped.class)` and `ShutdownEvent` is fired *before* `@Destroyed(ApplicationScoped.class)`. 
For a native executable build, however, `@Initialized(ApplicationScoped.class)` is fired as *part of the native build process*, whereas `StartupEvent` is fired when the native image is executed.
See <<writing-extensions.adoc#bootstrap-three-phases,Three Phases of Bootstrap and Quarkus Philosophy>> for more details.

NOTE: In CDI applications, an event with qualifier `@Initialized(ApplicationScoped.class)` is fired when the application context is initialized. See https://docs.jboss.org/cdi/spec/2.0/cdi-spec.html#application_context[the spec, window="_blank"] for more info.

== Package and run the application

Run the application with: `./mvnw compile quarkus:dev`, the logged message is printed.
When the application is stopped, the second log message is printed.

As usual, the application can be packaged using `./mvnw clean package` and executed using the `-runner.jar` file.
You can also generate the native executable using `./mvnw clean package -Pnative`.
